There's a lot of talk about philosophy and films, the idea being that films can actually do philosophy, not just that films can illustrate philosophy. Well, I wonder whether The Way - directed by Emilio Estevez, starring his father Martin Sheen - might count.

First, it is a sentimental film, not layered and edgy like Hitchcock, the philosopher's director of choice. Sheen plays an American who comes to Spain to bring home the remains of his dead son, only to discover that his son had died on the pilgrimage from the Pyrenees to the shrine of Santiago de Compostela, the Camino, the Way. He decides to do the pilgrimage for his son himself. As he walks, he picks up three other wounded souls - and I don't suppose there was a dry eye in the cinema by the time they reach their destination. And it seemed to me that the film did do some philosophy of religious experience in an interesting way too.

For one thing, the pilgrims are all religiously-indifferent, if not atheistic, and yet the journey touches them. The priority of experience over doctrinal belief is enacted. In fact, it's not clear that any of them are any more Christian by the end, though they clearly learn to trust the unexpectedness of what happens, to find faith.

The irrationality of the pilgrimage process is depicted throughout too, from the careful collection of passport stamps to the ludicrous swinging of the gigantic thurible in the cathedral at Compostela. This spoke of how the reconciliation they seek is not a rational process. If it was, they could have sat down and worked it out, not had to walk the hundreds of miles.

There were lots of other little details - how they are all rather unlikeable characters as a result of acting out their private agonies; how a kind of violence between them preceded any warming of hearts; how none of the explicit goals for the walk (losing weight, quitting cigarettes) were achieved but that what emerged was a new inner possibility.

I've a piece up on Cif Belief reflecting on good blasphemy and bad blasphemy, having read James Frey's new book. A taster:

Of course, Jesus was himself accused of blasphemy. In the story that will be rehearsed in churches during holy week, Jesus is asked by the high priest whether he's the son of the blessed one, and he responds: "I am." The high priest tears his clothes, saying: "You have heard the blasphemy."

It's usually religious authorities that declare something blasphemous because it challenges their religious power. The point here is that the life and death of Jesus show the world what God is like, Christians believe. Jesus is blasphemous because he challenges the notion that no one can see God and live, as Moses was told in the book of Exodus. It's a good blasphemy. It lies at the foundation of the new faith Jesus inspired. Perhaps new faiths always spring out of good blasphemy.

Actually, now I think about it again, it's not actually power that's at stake, but authority. The high priests have the authority of their institution, but little or no natural authority by virtue of who they are - which by all accounts, Jesus had in spades.

Incidentally, if you want to see how scientists do blasphemy, peruse the row over EO Wilson's switch from kin selection to group selection in evolutionary theory. Wilson's charge is that kin selection is accepted as the orthodoxy though few seem to have actually done the maths. (Wilson's collaborator, Martin Nowak, who has done the maths, was recently at the RSA.) Wilson is reported as saying, 'What we’ve done is clear the way for a new period of research, unencumbered by the doctrinaire aspects of kin selection theory.'

The scientists will fight it out, but on the face of it, group selection would seem to make much better sense of my interest in this area, the phenomenon of friendship, of which reciprocal altruism could never make much sense, or so it seems to me.

Is it just me, or has there been a little run of 'the self is a delusion' articles and talks around and about?

One used the analogy of a smart phone to deconstruct the sense of selfhood. Much as a smart phone contains applications that together make the phone smart, so the argument goes, the brain contains evolutionary applications - an emapthy app, a language app, a sex app - that together make a person. And personhood of itself is nothing more or less than the sum of those apps. But the analogy is flawed, and I suspect the psychology is too. A smart phone is not smart by virtue of its applications, no matter how sophisticated. It's smart because of the people who designed it and, crucially, because of the people who use it in smart ways too. You can't be rid of selfhood like that.

Another used the story about Sister Vagira who likened being a person to being a cart. There's the axle and wheels and carriage and springs. But the cart, it's said, is just the assembly of those elements, nothing more of itself. Only again, those elements are only a cart because of the people who assembled and designed it and because of those who drive it. You need a concept of personhood to understand a cart.

It may be very hard to say what an 'I' is, and it is surely multiple and porous. (It sadly needs repeating: Plato knew as much, and so did poor Descartes for that matter.) But don't rush too fast to concluding there's no 'I' at all. Better, surely, to rest with you and I being something of a mystery, deepened in the analysis, not dissolved in it.

I was listening to the RSA President's lecture given by David Attenborough - which is worth the time just to hear the Duke of Edinburgh speak too: he is very funny and very well informed, at almost 90 years old.

Attenborough's lecture is about the human population explosion and the damage that does to the natural world. By 2050, the world's population will have grown to 9.2 billion, if current predictions hold. Extinctions and degradations follow human habitation as night follows day. The message: curtail population, not by fiat, but by education, particularly of women, and economic development. With those advantages, people automatically have smaller families.

But I wondered if that is quite right. It strikes me that it is not population growth that does the damage, but economic development. After all, are not the most environmentally damaging nations today those with static populations? Clearly, if the population continues to grow, then escalating natural destruction will follow, though not to such an extent if it is not accompanied by economic development. And presumably the damage will continue even if the population levels off, as a result of the resource demands of economic development.

You could argue that technological advances are likely to allow economic growth to continue sustainably, though Attenborough also argues that 'sustainable growth' is ultimately an oxymoron on a planet with limited resources such as our own.

So whilst he was adamant that population growth is a taboo subject amongst politicians, which may well be so, I came away wondering whether it's a proxy issue, if the natural world is your concern.

There was a press screening of There Be Dragons in the UK yesterday - a new film by Roland Joffé (The Killing Fields, The Mission) about the escape from Spain, during the civil war, of Josemaria Escrivá, the founder of Opus Dei.

Turbulent times and an extraordinary person, whether you think Opus Dei is a conservative cabal or a company for compassion. But I have to say, I found the film rather catechetical and hagiographical. You can't argue against its central message: forgiveness not vengence. But compared with, say, Of Gods and Men, which is also about saints in a time of war, it lacked psychological depth and spiritual insight. I suspect that part of the problem is the film is, largely, funded by Opus Dei members - the producer is part of the movement too - and devotion doesn't make for critical distance. (Also, the film's distribution in the UK is being secured by a grassroots campaign, much like The Passion of the Christ.)

That said, reading the press pack on the way home, Joffé has this to say about Escrivá, concerning a characteristic of the man that grabbed the director as a 'wobbly agnostic', and me.

This love for God becomes an organising principle that gives him a shape and a kind of simplicity and strength. But that doesn't make him dull or flat, because this love existed in the real world, and the fruit of that existence in the real, often cruel, harsh world, must for any honest man be doubt: doubt in God and doubt in goodness. This doubt is deeply, profoundly, fertile.

Saints are flawed, like the rest of us. But if Joffé is right, Escrivá's heroism was that in spite of his doubts, and no doubt mistakes - or should that be, because of them - he 'never lost sight of the innate worth of each human being'. That is no mean feat during terrible times like the Spanish civil war.

I've had a couple of enquiries about what's new in How To Be An Agnostic, compared with the older edition, After Atheism.

(i) Introduction, has some new sections, and frames the question differently. Chapter 1 is revised slightly.

(ii) Chapter 2, on cosmic religion, as Einstein put it, is almost entirely new. It takes readers on a tour of the five different ways physicists find meaning in their science, or not - considering the spiritual significance of quantum physics, fine-tuning, consciousness and so on. I then, more briefly, look at the same trend amongst biologists. I then ask what we can make of science as inspiring new sacred stories.

(iii) Chapter 3, is on whether science can provide an underpinning for morality, and is largely new. It looks at recent work on happiness, empathy and fairness, and explores the links between religious traditions and virtue ethics.

(iv) Chapter 4, on being spiritual but not religious, is entirely new. It begins by asking why people call themselves spiritual but not religious, and asks whether we're in the midst of a spiritual crisis today. It then looks at a number of alternatives, particularly Western Buddhism.

(v) Chapters 5, 6 & 7 are broadly the same as before - with new material added here and there.

(vi) Chapter 8 is about half new - with longer entries on matters like Jesus, the probability of God, the agnostic spirit and silence.

The first part of radio series I've written and presented, In Doubt We Trust, goes out next Sunday on BBC Radio 4 - March 6, 1.30pm.

We spoke to a wide range of people in the making of it, exploring doubt not just in science and religion, but politics and economics, at a personal and philosophical level. Inevitably, there was too much to squeeze in. So, by way of a taster, here are three ideas that didn't make the final cut.

Ann Widdecombe: We live in an odd world, now, where doubt in relation to religion is almost mandatory for fear of intolerance, whereas doubt in relation to politics is almost forbidden.

Angie Hobbs: The ancient philosophers were better at doubt because they accepted their task was, in part, to embrace the limits of knowledge and show others how to live with that.

Rowan Williams: Doubting Thomas is often thought of as demanding hard evidence - unless I touch the wounds - and yet it was his encounter with the person of Christ that sparked faith.

I was hugely glad to catch the film, Of Gods and Men, at the end of its London release. What a powerful picture.

I found watching the character Luc, played by Michael Lonsdale, particularly moving. He seems the most reconciled of the monks as they face the nauseating uncertainties of violent death. I took it that his doctor's training had lent him the capacity to be with pain and not fear it. Hence, in life and then death, he was free.